Ten samples of root rot diseased Chinese ephedra were collected from the base of Chinese ephedra in Ningxia area of China during 2001. Pathogenicity of fungal isolates obtained from these samples was tested by verifial standard means of the Koch's Postulation. The results showed that the isolates mainly belonged to Fusarium spp. Infection analysis indicated that F. subglutinans had the strongest virulence with a diseased seedlings rate of more than 60%, whereas pathogenicity rate of F. oxysporum, F. semitectum, F. solani var. coeruleum and F. solani ranged from 10% to 20%. When F. subglutinans was co-inoculated with other isolates, the diseased indices of mixed inoculations were all higher than those of their individual infection. The combined inoculations of F. subglutinans with F. oxysporum or F. semitectum induced higher rates of diseased seedlings than those of F. subglutinans with other fungi. Our results revealed that F. subglutinans was the major pathogen of root rot disease of Chinese ephedra, whereas F. oxysporum, F. semitectum and the other two Fusarium species only played an accessory roles in the complex infection.